1. Field of the Invention
The present invention relates to an accumulator used in a vehicle, a trailer, hydraulic system and the like and, more particularly, to a hydro-pneumatic accumulator having a cylinder in which a liquid and a high-pressure gas are stored.
2. Description of the Related Art
A suspension apparatus generally used in a vehicle and the like comprises a suspension spring for supporting the weight of the vehicle body and a shock absorber. A coil spring or a leaf spring has been used as the suspension spring. In a hydro-pneumatic suspension apparatus previously developed by the present inventor, however, a bellows is housed in a cylinder, so that the interior of the cylinder is partitioned by the bellows into an oil chamber and a gas chamber.
A gas having a high pressure (8 kg/cm.sup.2 l or more) is sealed in the gas chamber. When the weight of the vehicle body is loaded, a pressure of the gas is 10.about.70 kgf/cm.sup.2 at lower bound and 50.about.350 kgf/cm.sup.2 at upper bound. When the gas is supplied into the cylinder, the bellows is axially deflected by the pressure of the gas. In this case, deflection means expansion or contraction of the bellows. In order to prevent deflection of the bellows from exceeding an allowable limit, the present inventor proposed to arrange a stopper at a position where an end face of the bellows can be supported when it is deflected by an amount exceeding a predetermined value. This stopper has a plate-like or cylindrical shape and is arranged at a position opposite to the distal end of the bellows in the cylinder.
It was found, however, that even if axial deflection of the bellows is suppressed within a predetermined limit by the stopper, the bellows is radially deformed when the pressure of a gas is high. Especially, in a case wherein a metal bellows is used, if plastic deformation of the bellows occurs its normal shape cannot be restored again. Hence, a portion subjected to plastic deformation becomes a fatal defect. In addition, in order to incorporate the plate-like or cylindrical stopper in the cylinder, a specific space for housing the stopper must be ensured in the cylinder. Moreover, extra measures must be taken to fix the stopper to the cylinder, and hence the arrangement of the cylinder becomes complicated.